The invention relates to a measurement method of time varying events in a target body.
Particularly the invention relates to a measurement method in which time dependent events are measured by means of several probes or devices capable of detecting and monitoring different parameters and among which also an ecographic imaging method is used.
Time varying events are often connected to motion or change in shape of a target body or parts thereof and these events can be measured or detected by means of ecographic, i.e. ultrasound imaging methods and devices.
M-mode ecographic images are useful instruments for measuring, monitoring or detecting the dynamic of biological targets and of unanimated targets as for example it is well known in echocardiology and in the assessment of industrial valvular dynamics to flying or deformable objects.
The so-called M-mode (Motion-mode) images, a name mostly used in echocardiography, is a two-dimensional image representation where one axis, normally the abscissa, is the time direction, and one axis is one space line or curve within a higher dimensional space along which a signal is recorded (FIGS. 1, 2). The M-mode representation is obtained in echographic instruments by a direct recording of the ultrasound signal received along a scanline (FIG. 1).
More recently methods for generating and display M-mode images where the spatial direction is not restricted to be along a scanline have been introduced (FIG. 2). These methods, that permit to create a M-mode image from a sequence of echographic images, are described in
U.S. Pat. No. 5,515,856 (1996 Vingmed), also RE37,088 “Method for generating anatomical M-mode displays”;
U.S. Pat. No. 5,820,561 (1996 Vingmed), “Analysis and measurement of temporal tissue velocity information”;
U.S. Pat. No. 6,589,175 (Philips), “Real-time arbitrary mmode for ultrasonic imaging system”.
More recently, the use of M-mode images for the quantitative analysis of time-varying quantities on a sequence of images has been introduced in
WO 03 071950 (AMID SRL) also PCT/IT02/00114 filed on Feb. 27, 2002, “M-tracking for space-time imaging”.
A further application based on the combined sequence of quantitative analysis of M-mode images has been introduced in EP 03 42 5639 (Esaote SPA, AMID SRL) filed on Sep. 30, 2003 entitled “A method of tracking position and velocity of objects' borders in two or three dimensional digital images, particularly in echographic images” in which application the method of creating the M-mode image from line or curve draw on one frame of a sequence of images, has been further improved by using a line or curve with a thickness that is larger than a single pixel and taking the average signal value across such thickness. This improvement allows to generate M-mode images that are less noisy than those obtained from regular M-mode.
The M-mode representation is widely used in echocardiography for the assessment of mechanical timings, like contraction of cardiac chamber, valvular opening etc. This representation is very important in diagnosis and indeed the mechanical timing is employed in conjunction with timing of electrical events, electrocardiogram (ECG).
Other parameters which describes, are generated or related to the time varying event in the target body can be obtained by measuring different physical or physiological effects by means of probes which reacts to the effects and generate a corresponding time dependent measurement signal generally an electric or electromagnetic signal. The electrocardiogram is an example of such kind of apparatus which furnishes a time dependent electric measurement signal related to the cardiac activity.
In most field, the principal graphic display of dynamic quantities i.e. of the time dependent measurement signal or of a signal obtained by further treating the measurement signal for the extraction of the relevant part of information desired, is the presentation in the form of a XY graph of a function y=ƒ(t) where t is the time, or the abscissa, typically the horizontal axis, y is the ordinate, and f is a generic functional relationship that can be mathematically known (explicitly or implicitly), be the result of a computation or of measurements. Such a representation shows the evolution of one or more quantities in time (FIG. 3).
It is known to associate measurements of a target body made by means of ultrasound imaging methods with measurements of one or more of other relevant parameters by means of probes furnishing time dependent signals in the meaning defined above.
Nevertheless this time dependent measurement signals are used basically for triggering the ecographic image acquisition and are displayed in a separate manner.
Present known methods do not offer a way to reveal and explicit show dynamic relations between the different time dependent measurements signals and the information of the ecographic images.
The present invention aims to improve the present measurement methods by allowing in a simple, rapid and non expensive way to reveal and recognize immediately dynamic relationships between the different measurements signals and the ecographic images.
The present invention achieves the above mentioned aims by means of a measurement method of time varying events in a target body, comprising the steps of:
a) Providing one or more time dependent measurements signals of one or more parameters of the time varying events in the target body by means of one or more measurement devices or probes;
b) Providing one or more ecographic M-mode (Motion mode) image data where the space direction is along one or more scan-lines or curves;
c) defining a time interval within which the measurement signals has to be displayed and/or evaluated;
d) defining a time instant of begin of the said time interval having a univoquely relation to one or more time varying events;
e) generating a bi-dimensional graph of the function corresponding to each said time dependent measurement signal one direction of the said bi-dimensional graph being the time axis;
f) generating one or more bi-dimensional M-mode images, the time axis being chosen as having the same direction of the graph of the function corresponding to the said time dependent measurement signals;
g) determining in each graph of the function corresponding to each said time dependent measurement signal and in the M-mode images the time instant of begin of the said time interval having a univoquely relation to one or more time varying events;
h) resealing the time scale of each graph of the function corresponding to each said time dependent measurement signal and of the M-mode images to a unique and identical time scale in which the said defined time interval has an equal length along the time axis;
i) displaying the graph of the function corresponding to one or more of the said time dependent measurement signal on a background formed by one or more of the M-mode images by aligning the said time instant of begin of the said time interval in a coincident position.
Advantageously the colours or shades of the graph of the function corresponding to one or more of the said time dependent measurement signal and of the M-mode images are modified in order to be different form each other.
In order to harmonize the dimensions of the said graphs and of the said M-mode images, the graphs of the function corresponding to one or more of the said time dependent measurement signal and/or the M-mode images are extended or reduced in a direction orthogonal to the time axis
When at least two M-mode images are provided these can be displayed one adjacent to the other in a direction orthogonal to the time axis. Similarly when at least two graphs representing the function corresponding to the time dependent measurement signal of two different parameters are provided these can be displayed shifted one with respect to the other in a direction orthogonal to the time axis.
At least part or all of the ecographic data for generating the M-mode images and of the time dependent measurement signals are measured or acquired during the same time.
At least part or all of the ecographic data for generating the M-mode images and of the time dependent measurement signals are measured or acquired during different times.
According to a further feature the ecographic data for generating one or more of the M-mode images may be directly acquired by a repeated firing of ultrasound beams and by receiving of the reflected ultrasound beams along a scan line at least for a time period corresponding to the said defined time period.
It is also possible that the ecographic data for generating one or more of the M-mode images is reconstructed form a time sequence of two dimensional or three dimensional ecographic image data by defining at least a scan line and reconstructing the image data along the said scan-line from the intersection of the said scan-line with the two or three dimensional ecographic image data as disclosed in the above cited references.
The scan lines of at least one of the M-mode images may be chosen having a rectilinear shape or an arbitrary curved shape.
Further improvements and features of the present invention are subject of the dependent claims.
The above innovative approach allows to combined the display of different quantities and the immediate comparison of their dynamics. It has a formidable impact for the improvement of the diagnostic capability in cardiology.
The measurement method according to the present invention can be directed to target bodies being a biologic body or an anatomical district or a part of an anatomical district of a biological being and particularly to the cardiac district and tissues.
In this case the time dependent measurement signal is an electrocardiogram (ECG) signal and the at least one M-mode image is an echocardiographic image.
In a particularly advantageous embodiment the scan line along which the echocardiographic image is taken is chosen so to cross one or more ventricular tissue elements particularly the annulus and the anterior mitral valve leaflet and/or the ventricle wall.
Further time dependent signals can be measured and displayed consisting for example in the time profile of the left ventricular volume and/or the strain of the lateral wall and/or the strain of the intraventricular septum.
The invention relates furthermore to a method for displaying measurement data of different parameters of a target in which time dependent events occur, which measurement data consist in at least an ecographic M-mode image and in at least a two dimensional graph representing a time dependent measurement signal, the said method comprising the steps of displaying the two dimensional graph laid over the M-mode image as a background.
More particularly the said method comprises the following steps:
a) defining a time interval within which the measurement data has to be displayed and/or evaluated;
b) defining a time instant of begin of the said time interval having a univoquely relation to one or more time varying events;
c) generating a bi-dimensional graph of the function corresponding to the said at least one time dependent measurement signal, one direction of the said bi-dimensional graph being the time axis;
d) generating a bi-dimensional M-mode image the time axis being chosen as having the same direction of the graph of the function corresponding to the said time dependent measurement signal;
e) determining in each graph of the function corresponding to the said at least one time dependent measurement signal and in the at least one M-mode image the time instant of begin of the said time interval having a univoquely relation to one or more time varying events;
f) rescaling the time scale of the graph of the function corresponding to the said at least one time dependent measurement signal and of the at least M-mode images to a unique and identical time scale in which the said defined time interval has an equal length along the time axis;
i) displaying the graph of the function corresponding to the said at least one time dependent measurement signal on a background formed by the said at least one M-mode images by aligning the said time instant of begin of the said time interval in a coincident position.
Further details or improvement of the said method are disclosed in the dependent claims.
The features and the advantages of the present invention will be disclosed in greater detail in the following description of some examples and by the annexed drawings.